Sealed gas burners are well known in the art and are normally disposed around a burner opening of a range top and secured in place around the periphery of the opening so that any spillage of food will remain on the range top and not pass between the burner head and the burner opening into the interior of the range. This type of assembly provides a streamline appearance which facilitates the cleaning and maintenance of the range top.
A sealed burner assembly typically includes a burner cap with a sidewall having a plurality of burner ports formed therein and through which the primary air/gas mixture is passed to the exterior of the burner cap for combustion. An electrode connected to an appropriate electrical circuit terminates on the exterior of the burner cap for providing spark ignition for the air/gas mixture. The use of spark ignition has become increasingly popular because it avoids the unnecessary energy consumption required by a standing ignitor pilot flame that has been used in the past to ignite gas range top burners. The electrode of the spark ignition system is normally in the form of a wire which extends upwardly through the base of the burner and is supported therein by an electrically insulated member. Various electrode designs have been proffered which include internal electrodes extending through the base into the gas chamber and exiting the gas chamber through the sidewall of the burner; and external electrodes protruding through the base and extending adjacent to the sidewall of the burner. The burner cap is manufactured from an electrically conductive material and is electrically connected to the range top which serves as an electrical ground potential for the spark ignition system. The electrode is electrically connected to a high voltage potential electrical circuit for providing ignition sparks between the electrode and the burner cap. The ignition sparks ignite the primary air/gas mixture passing through the burner ports to create the desired burner flame which is then supported by the secondary ambient air.
There are many known problems and disadvantages associated with prior art sealed gas burner assemblies, and particularly those provided with internal spark ignitors. For example, the spark created by the electrode jumps from the electrode to the burner body and ignites the primary air/gas mixture that flows through the spark. This ignition is difficult to achieve in a drawn sheet metal burner cap using an internal electrode because the main portion of the electrode is contained within the burner head to protect it from food spillovers. Since only the tip of the electrode protrudes out through the electrode aperture in the sidewall of the burner head, there is a tendency for the spark to randomly jump to the burner body in all directions, thus providing for a somewhat unreliable ignition of the primary air/gas mixture. A prior art attempt to overcome this problem with internal electrodes involves adding gas pathways formed integral with the electrode body or integral with the electrode aperture. These gas pathways are so located that during the sparking of the electrode in random directions, the gas will hopefully become ignited within a specified period of time. This arrangement is not entirely reliable and addition of the integral pathways create a tool maintenance problem in the manufacturing of the burner assembly.
The designs of external electrodes which protrude from the base and extend adjacent to the exterior sidewall, while generating a more consistent spark pattern, suffer from the disadvantage that the electrode is susceptible to damage and/or food spills due to its location on the outside of the burner body. These disadvantages of the external electrode led to the development of the internal electrode with the opinion that the randomness pattern of the spark of an internal electrode was less of a problem than the susceptibility of damage and/or food spills associated with the external electrode.
Accordingly, there is a need for a spark ignition system which can provide a more consistent spark pattern to increase the reliability of the primary air/gas ignition while at the same time providing protection for the electrode from damage and/or food spills.